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Natural Environment How Human History has been impacted by the environment, science, nature, geography, weather, and natural phenomena


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Old December 4th, 2017, 09:08 AM   #11
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I pray on my knees for a Neanderthal having survived by the same way ,
there was interbreeding , but so far it seems that the Neanderthal are gone
This is a very strange thing to say. Neanderthals did survive in exactly the same way as the archaic West African population that contributed the highly divergent Y-chromosome. They interbred with our ancestors (which is perhaps the wrong way to put it - since they are also our ancestors - our majority ancestors?).

Neanderthal genes survive in populations today, just as the archaic West African genes do - I'm unsure what difference you're seeing. If there is a difference; it's that Neanderthals have contributed a hell of a lot more to the modern gene pool. Almost all of us carry DNA inherited from Neanderthals.

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I would say that our immune system was better than theirs. While we may have killed some off, it is more likely that we could adapt to viruses and bacteria that they could not, which made us carriers of their extinction.
We know this is very unlikely for one simple reason. When we look at the Neanderthal genes we have inherited; we see a lot related to immune system functioning. This makes sense - the expanding African population moving into Europe and Asia may have had some advantages over the Neanderthals they encountered; but the Neanderthals had already had tens of thousands of years to adapt to local pathogens. The immune system was unlikely to have be a problem for Neanderthals - it was probably one of their biggest advantages.
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Old December 4th, 2017, 10:40 AM   #12

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We know this is very unlikely for one simple reason. When we look at the Neanderthal genes we have inherited; we see a lot related to immune system functioning. This makes sense - the expanding African population moving into Europe and Asia may have had some advantages over the Neanderthals they encountered; but the Neanderthals had already had tens of thousands of years to adapt to local pathogens. The immune system was unlikely to have be a problem for Neanderthals - it was probably one of their biggest advantages.
Well, let's compare the events of Europeans reaching the Americas to humans reaching Europe and Asia. The Indigenous tribes had been in the Americas for thousands of years and were human, but the diseases the Europeans brought devastated the populations. The same argument about a similar immune system could be made for them, but there were other factors to consider. So, while the Neanderthal immune may have been similar, they may simply not have had a gradual exposure to viruses from Africa that humans had, resulting in their populations being decimated.

So, perhaps it was not a case of a better immune system, but just a matter of more time to adapt to mutating viruses. We may not be able to tell for sure, but there is something that contradicts the theory of complete annihilation by killing, and that is that humans did not completely annihilate other species. This was not because the instinct to kill was missing, it was there, but other species were not prone to the same illnesses that we were.
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Old December 4th, 2017, 11:40 AM   #13
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Well, let's compare the events of Europeans reaching the Americas to humans reaching Europe and Asia. The Indigenous tribes had been in the Americas for thousands of years and were human, but the diseases the Europeans brought devastated the populations. The same argument about a similar immune system could be made for them, but there were other factors to consider. So, while the Neanderthal immune may have been similar, they may simply not have had a gradual exposure to viruses from Africa that humans had, resulting in their populations being decimated.

So, perhaps it was not a case of a better immune system, but just a matter of more time to adapt to mutating viruses. We may not be able to tell for sure, but there is something that contradicts the theory of complete annihilation by killing, and that is that humans did not completely annihilate other species. This was not because the instinct to kill was missing, it was there, but other species were not prone to the same illnesses that we were.
We didn't annihilate anyone though - that's the whole point. Modern humans didn't wipe out Neanderthals - they settled down and had families with them. The question shouldn't be 'why did Neanderthals die out', because they didn't - the question is 'why did we inherit such a small percentage of Neanderthal DNA.

The easiest explanation would be numbers - the modern human population simply swamped the Neanderthals. That could be due to greater absolute numbers; or due to a faster reproductive rate.

I find it unlikely that the modern human immune system was selectively advantageous because, as I said, non-Africans inherited a lot of immune-linked genes from Neanderthals - this suggests they had a lot of immune advantages in European and Asian environments. The arrival of old world diseases to the Americas is not a good comparison, because these were diseases cultivated over centuries of animal domestication and urbanism - no such diseases existed in the Pleistocene.
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Old December 4th, 2017, 03:05 PM   #14

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We didn't annihilate anyone though - that's the whole point. Modern humans didn't wipe out Neanderthals - they settled down and had families with them. The question shouldn't be 'why did Neanderthals die out', because they didn't - the question is 'why did we inherit such a small percentage of Neanderthal DNA.

The easiest explanation would be numbers - the modern human population simply swamped the Neanderthals. That could be due to greater absolute numbers; or due to a faster reproductive rate.

I find it unlikely that the modern human immune system was selectively advantageous because, as I said, non-Africans inherited a lot of immune-linked genes from Neanderthals - this suggests they had a lot of immune advantages in European and Asian environments. The arrival of old world diseases to the Americas is not a good comparison, because these were diseases cultivated over centuries of animal domestication and urbanism - no such diseases existed in the Pleistocene.
There is another explanation that is far more likely. When humans began to arrive in Europe and Asia, they encountered the Neanderthals, who, as you mentioned before, had been there for thousands of years and had become established and organized. The arrival of small groups of humans put the humans at a disadvantage, the same way that small groups of immigrants entering a new country face. Neanderthal males, with their bigger numbers and better knowledge of the area, overpowered the human males and killed them. They took the females for themselves and impregnated them, but that exposed them to the viruses that humans carried. As the Neanderthal populations died off, some human females still had the babies they carried, and that is where the small traces of DNA in us come from.
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Old December 5th, 2017, 08:08 AM   #15

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Well, the other primate species were not human (that is, "homo sapies") so it is quite misleading to say that we are the only humans that are left. We are the only humans that ever were.
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Old December 5th, 2017, 09:46 AM   #16
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Im interested to know how the homosapiens came about during the neanderthals? A small population breeding in a secluded area for hundreds of years? Do we know who the Homo sapiens evolved from? If so, why did some become neanderthals and other Homo sapiens.
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Old December 5th, 2017, 09:55 AM   #17
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There is another explanation that is far more likely. When humans began to arrive in Europe and Asia, they encountered the Neanderthals, who, as you mentioned before, had been there for thousands of years and had become established and organized. The arrival of small groups of humans put the humans at a disadvantage, the same way that small groups of immigrants entering a new country face. Neanderthal males, with their bigger numbers and better knowledge of the area, overpowered the human males and killed them. They took the females for themselves and impregnated them, but that exposed them to the viruses that humans carried. As the Neanderthal populations died off, some human females still had the babies they carried, and that is where the small traces of DNA in us come from.
This is in no sense 'far more likely'. For starters, it's quite a specific scenario, and any specific scenario is a priori unlikely. Modern human-Neanderthal interaction was not a one-off event; and it did not happen over a short time period. The pattern of Neanderthal genes in todays humans (which are different in different parts of the world) suggest at least three major episodes of interbreeding. In the Middle East, we have remains from Skhul and Qafzeh which are generally interpreted as modern human from about 100,000 years ago; and then we have remains from the same area 70,000 years ago usually classed as Neanderthals. We should perhaps be careful about how easy it is to assign skulls to one population or the other - especially now we know that they interbred - but any explanation which is taking place on a human-like timescale is not an explanation. Neanderthals and modern humans shared the world for tens of thousands of years.

There's no reason to think that modern humans carried viruses the Neanderthals couldn't deal with. It's possible, of course, but it's totally unevidenced. We do know, however, that Neanderthals did not simply die after breeding with modern humans. What we're trying to explain is not just the presence of Neanderthal genes in our genome; since the genome of a Neanderthal woman who died in Siberia 50,000 years ago shows that modern human genes passed the other way.
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Old December 5th, 2017, 10:13 AM   #18
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Well, the other primate species were not human (that is, "homo sapies") so it is quite misleading to say that we are the only humans that are left. We are the only humans that ever were.
That depends what you mean by 'human'. Some researchers do classify Neanderthals as Homo sapiens, but if they are classed as a separate species then 'human' is clearly not limited to our species. If bipedal, tool-using apes that wore tailored clothes and built composite tools are not human, then I'm not sure what the term means.

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Im interested to know how the homosapiens came about during the neanderthals? A small population breeding in a secluded area for hundreds of years? Do we know who the Homo sapiens evolved from? If so, why did some become neanderthals and other Homo sapiens.
Neanderthals did not live all over the world - they lived only in Europe and parts of Asia. The people we normally think of as modern humans evolved in Africa - but they weren't some small, isolated population. On the contrary, the population of Africa was much larger - especially than Europe, parts of which kept being overrun by ice. If anything, it was the Neanderthals living in Europe and northern Asia who were the small, secluded populations.

It might be wrong to think of Neanderthals as modern humans as different species, though. It might make more sense to think of Homo sapiens as already living all across the Old World 100,000 years ago - but then it's only important to keep in mind that it was a much more structured population than today's. Today's humans spread across the world very recently, in the scale of things, and different populations have not been very isolated - there's been a lot of interbreeding going on over the centuries. All this means that, despite how superficially different a Tibetan might look from a Nigerian, we're actually all pretty closely related. A Tibetan and a Nigerian are much more similar genetically than a chimpanzee from Guinea and a chimpanzee from the Congo. Our population is not very structured, meaning that everyone's quite genetically similar, and the genetic difference that do exist tend to happen in smooth gradients.

100,000 years ago, however, things were much different. The subpopulations of humans in different parts of the world came into contact much less, and so were more distinct from each other genetically and physically. There would have been clearer dividing lines, probably matching natural barriers to movement, with more clearly distinct populations living on each side. But they weren't completely isolated. People still moved about and came into contact, populations displaced each other, and these distinct populations exchanged genes - so they were still having sex at least occasionally.
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Old December 5th, 2017, 10:42 AM   #19

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The domestication of the wolf may have had something to with it. There is a hypothesis that our species was able to out-compete Neanderthals for food because their hunts were aided by Fido.

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With their large brains, sturdy physique, sophisticated tools, and hunting skills, Neanderthals are the closest known relatives to humans. Approximately 200,000 years ago, as modern humans began to radiate out from their evolutionary birthplace in Africa, Neanderthals were already thriving in Europe―descendants of a much earlier migration of the African genus Homo. But when modern humans eventually made their way to Europe 45,000 years ago, Neanderthals suddenly vanished. Ever since the first Neanderthal bones were identified in 1856, scientists have been vexed by the question, why did modern humans survive while their evolutionary cousins went extinct?

The Invaders musters compelling evidence to show that the major factor in the Neanderthals’ demise was direct competition with newly arriving humans. Drawing on insights from the field of invasion biology, which predicts that the species ecologically closest to the invasive predator will face the greatest competition, Pat Shipman traces the devastating impact of a growing human population: reduction of Neanderthals’ geographic range, isolation into small groups, and loss of genetic diversity.

But modern humans were not the only invaders who competed with Neanderthals for big game. Shipman reveals fascinating confirmation of humans’ partnership with the first domesticated wolf-dogs soon after Neanderthals first began to disappear. This alliance between two predator species, she hypothesizes, made possible an unprecedented degree of success in hunting large Ice Age mammals―a distinct and ultimately decisive advantage for humans over Neanderthals at a time when climate change made both groups vulnerable.
The Invaders: How Humans and Their Dogs Drove Neanderthals to Extinction
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Old December 5th, 2017, 12:26 PM   #20

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the usual marker for a specie is if it can interbreed and produce fertile offspring
since there is some evidence for interbreeding one can assume that Neanderthal and Cro-Magnon people were of the same homo Sapiens specie

It is true that the Neanderthal gene pool was smaller than the Africa based Cro-Magnon antecedors

The domestication of the dog is not proven before the end of the last ice age , by which time the last few surviving Neanderthal were on the way out in the south of Spain
the Cro Magnon toolkit was much more varied than the Neanderthal one , indicating a greater range of food source
There is a lively debate about the Neanderthal adopting (or not) some of the new techniques

while tools change , behavior do not , Homo sapiens Sapiens has a solid track record as killer
while it's expansion was quire slow at first in the Middle East , the European expansion was brutal and fast , indicating to my eyes a conflictual encounter ,
it should be noted than the Western Neanderthal were quite extreme in their morphology and would have been seen as very different to the Cro- Magnon
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